Diogenes Laertius Vitae philosophorum 6.2.73

[73] And he saw no impropriety either in stealing anything from a temple or in eating the flesh of any animal; nor even anything impious in touching human flesh, this, he said, being clear from the custom of some foreign nations. Moreover, according to right reason, as he put it, all elements are contained in all things and pervade everything: since not only is meat a constituent of bread, but bread of vegetables; and all other bodies also, by means of certain invisible passages and particles, find their way in and unite with all substances in the form of vapour. This he makes plain in the Thyestes, if the tragedies are really his and not the work of his friend Philiscus of Aegina or of Pasiphon, the son of Lucian, ¹ who according to Favorinus in his Miscellaneous History wrote them after the death of Diogenes. He held that we should neglect music, geometry, astronomy, and the like studies, as useless and unnecessary.